· Optionally, expand envelope recipients
according to information found in the virtual(5) lookup
tables.

The cleanup(8) daemon performs sanity checks on the
content of each message. When it finds a problem, by default
it returns a diagnostic status to the client, and leaves it
up to the client to deal with the problem. Alternatively,
the client can request the cleanup(8) daemon to bounce the
message back to the sender in case of trouble.

enable_errors_to (no) Report mail delivery errors to the
address specified with the non-standard Errors-To: message
header, instead of the envelope sender address (this feature
is removed with Postfix version 2.2, is turned off by
default with Postfix version 2.1, and is always turned on
with older Postfix versions).

body_checks_size_limit (51200) How much text in a
message body segment (or attachment, if you prefer to use
that term) is subjected to body_checks inspection.

mime_header_checks ($header_checks) Optional lookup
tables for content inspection of MIME related message
headers, as described in the header_checks(5) manual
page.

nested_header_checks ($header_checks) Optional lookup
tables for content inspection of non-MIME mes- sage headers
in attached messages, as described in the header_checks(5)
manual page.

Available in Postfix version 2.3 and later:

message_reject_characters (empty) The set of characters
that Postfix will reject in message con- tent.

message_strip_characters (empty) The set of characters
that Postfix will remove from message con- tent.

BEFORE QUEUE MILTER CONTROLS As of version 2.3, Postfix
supports the Sendmail version 8 Milter (mail filter)
protocol. When mail is not received via the smtpd(8) server,
the cleanup(8) server will simulate SMTP events to the
extent that this is possible. For details see the
MILTER_README document.

non_smtpd_milters (empty) A list of Milter (mail filter)
applications for new mail that does not arrive via the
Postfix smtpd(8) server.

milter_protocol (6) The mail filter protocol version and
optional protocol exten- sions for communication with a
Milter application; prior to Postfix 2.6 the default
protocol is 2.

milter_default_action (tempfail) The default action when
a Milter (mail filter) application is unavailable or
mis-configured.

masquerade_domains (empty) Optional list of domains
whose subdomain structure will be stripped off in email
addresses.

masquerade_exceptions (empty) Optional list of user
names that are not subjected to address masquerading, even
when their address matches $masquer- ade_domains.

propagate_unmatched_extensions (canonical, virtual) What
address lookup tables copy an address extension from the
lookup key to the lookup result.

Available before Postfix version 2.0:

virtual_maps (empty) Optional lookup tables with a)
names of domains for which all addresses are aliased to
addresses in other local or remote domains, and b) addresses
that are aliased to addresses in other local or remote
domains.

Available in Postfix version 2.0 and later:

virtual_alias_maps ($virtual_maps) Optional lookup
tables that alias specific mail addresses or domains to
other local or remote address.

remote_header_rewrite_domain (empty) Dont rewrite
message headers from remote clients at all when this
parameter is empty; otherwise, rewrite message headers and
append the specified domain name to incomplete
addresses.

RESOURCE AND RATE CONTROLS duplicate_filter_limit (1000)
The maximal number of addresses remembered by the address
dupli- cate filter for aliases(5) or virtual(5) alias
expansion, or for showq(8) queue displays.

header_size_limit (102400) The maximal amount of memory
in bytes for storing a message header.

hopcount_limit (50) The maximal number of Received:
message headers that is allowed in the primary message
headers.

in_flow_delay (1s) Time to pause before accepting a new
message, when the message arrival rate exceeds the message
delivery rate.

message_size_limit (10240000) The maximal size in bytes
of a message, including envelope information.

Available in Postfix version 2.0 and later:

header_address_token_limit (10240) The maximal number of
address tokens are allowed in an address message header.